Hot gas reciprocating engine with working medium augmenting means



9 1952 J w L. KOHLER 2,607,190

HOT GAS R ECIROCATING ENGINE WITH WORKING MEDIUM AUGMENTING MEANS Filed June 21, 1949 INVENTQR. QHCOB MLLHJMURHLIYKQZZLER Patented Aug. 19, 1952 2,607,190 nor .GAS nscrmocerme ENGINE .wr'rn- WOR-KING MEDIUM AUGMENTING MEANS I Jacob Willem Laurens Kiihler, Eindhovenrl j Netherlands, assignor to Hartford National Bank and Trust Company, Hartford, Conn., as

trustee I Application June 21, 1949, Serial No. 100,499 In the Netherlands July 27, 1948 2 Claims.

It is a known phenomenon that in hot-gas reciprocating engines of the closed cycle type (which term is to be understood to include refrigerating machines operating according to the reversed hot-gas engine principle wherein a quantity of working medium is continuously enclosed in the workingspace throughout the cycle of operation) working medium leaks away in time. This leakage of working medium results in a decrease in the power of the engine. It is therefore common practiceto replenish the quantity'of working medium periodically-in order to restore the power to its'original level. -As a rule, in replenishing the working medium use is made .of the control-system. provided in the engine. However, such control-systems generally comprise moving parts, the energy required for actuating these parts being supplied by the engine itself. When this control-system is used frequently for replenishing'the working medium,

the energy required for actuating the parts of the control-system may assume a value which cannot be neglected. In this case th mechanical losses of the engine thus increase.

The object of the invention is to provide a closed cycle hot-gas reciprocating engine in which the working medium is replenished in a simple manner, the mechanical losses of the engine not being substantially increased.

According to the invention a hot-gas reciprocating engine is characterized in that provision is made of means comprising a communication duct providing continuous communication between the working space and asecond space containing a supply of working medium, said means being such that the power output of the engine under operating conditions is decreased by no more than 5%, preferably by no more than 10 due to the presence of said means.

During that part of the cycle in which the pressure in the working space is lower than the pressure in the auxiliary space, a certain quantity of working medium will flow through the communication duct between the two spaces to the working space, whilst during that part of the cycle in which the pressure in the working space exceeds that in the auxiliary space, a certain quantity of working medium will flow through the communication duct to the auxiliary space.

When working medium leaks away from the working space, the quantity of working medium flowing to the working space will, since the mean pressure in the engine drops, be greater than the quantity of medium flowing to the auxiliary space.

To ensure satisfactory operation of the device for replenishing the medium, it is of importance that the resistance to flow in the communication duct shouldbe so small that it is possible, having regard to the pressure diflerence's between-working space and auxiliary space, to replace the quantity of medium leaked away, and should be so high that the flow of working medium through the communication duct during a cycle substantially does not affect the power output of the engine. Furthermore, it is of importance that the clearance volume of the communication duct should be so small that the power of the engine is not decreased excessively thereby.

Since, as a rule, the leakage losses of a closed cycle hot-gas reciprocating engine increase with increase in the time the engine has been continuously in use, it is advantageous if the resistance to flow in the-communicationduct is variable; itis thus possible to" control the replenishment of medium; in accordance with the leakage losses.

In one preferred embodiment of the invention, this communication duct is in the form of a tube. It is possible to shape the communication duct in difierent forms, for example, to be circular, annular, and so forth. The duct is preferably so shaped that the resistance to flow is as far as possible equal in both directions.

The communication duct may be of porous material.

It is obvious that the resistance to flow between the working space and auxiliary space may alternatively be provided in various other ways, for example by filling up at least part of the duct by fine wire material and the like, or by providing one or more narrow apertures therein. In the latter case it is possible that the narrow apertures form a labyrinth, for example, a number of narrow and wide apertures may be provided in series. It is furthermore possible to narrow the apertures, for example, by obturating one or more channels to. a smaller or greater extent by one or more screws. The rate of replenishing may thus be varied.

If it is not necessary that the power of the hot-gas reciprocating engine should be varied rapidly, the replenishing device may also be used for controlling the power output of the engine. For this purpose it is required that either the pressure in the auxiliary space or the resistance to flow in the duct, at substantially invariable leakage losses, should be varied for the power output of the engine to be also varied.

In certain cases. it may be desirable to have the mean pressure of the engine equal to the atmospheric pressure; in this case the auxiliary space may be constituted by the ambient free atmosphere. 7

In order that the invention may be more clearly understood and readily carried into effect, it will now be described more fully with reference to the accompanying drawing, showing diagrammatically, by way of examp1e,fone embodiment of a closed cycle hot-gas reciprocating engine according to the invention.

The closed cycle hot-gas reciprocating engine comprises a cylinder 1, in which a displacer 2 and a piston 3 are adapted to move. The piston 3 drives a crank shaft 5 through a driving rod 4, the displacer 2 being moved up and down, with the use of a rod system 6, taken through the piston 3, due to the rotation of the crank shaft. The movements of piston 3 and the displacer 2 take place with a constant phase difference. The enclosed working space of the engine comprises a hot space I and a cold space 8, which communicate with one another by way of-a heater 9, a regenerator l0 and a cooler Ii.

In the auxiliary.

space I3, so that the device l2, l3, l4 may be said enclosed working space, conduit means continuously connecting said two spaces, said conduit means comprising means to resist equally the flow of working medium therethrough in either direction of W thereof. I

2. A closed cycle hot-gas'reciprocating engine comprising means defining an enclosed working space therein for enclosing the working medium, means defining an auxiliary space separate from said enclosed working space, conduit means continuously connecting said two spaces, said conduit means comprising means to resist equally the flow of working medium therethrough in either direction of flow thereof, and a porous material at least partly filling said conduit means.

JACOB WILLEM LAURENS KOHLER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 270,036 Eimecke Jan. 2, 1883 324,060 Woodbury et al. Aug. 11, 1885 336,093 Daelen 1 Feb 16, 1886 623,137 Creuzbaur Apr. 18, 1899 815,732 Parr et a1. Mar. 20, 1906 855,442 Bickerton et al June 4,1907

1,091,904 Wullenweber Mar. 31,1914 1,764,110 Lundgaard June 17, 1930 2,042,969 Snyder June 2, 1936 2,089,224 Peterson et al Aug. 10, 1937 2,185,940 Dudley Jan. 2, 1940 2,547,781 Rinia et al. Apr. 3, 1951 FOREIGN PATENTS Number Country Date 15,048 Germany Aug. 24, 1881 

